The present invention relates generally to DC/DC power conversion and more particularly, relates to an optimized phase and frequency shifted power converter controller for an interleaved zero voltage switching (ZVS) forward power converter.
In regulated switching DC power supplies, DC/DC power converter circuits accomplish transformation of a DC voltage from one level to another. Solid-state devices, such as transistors, typically are operated as switches, either completely ON or completely OFF with these switching power converters. Since the switching devices are not operated in their active region, this operational mode results in lower power dissipation than linear power supplies. Increasing switching speeds, higher voltage and current ratings of the switching devices are some of the advantages that have increased the popularity of switching power supplies.
For example, switching power supplies may have a switching frequency of 100 KHz or higher. The high switching frequencies permit the components utilized in the construction of the power converter, such as capacitors, inductors and transformers, to be physically small. The overall generally small size also has increased the popularity of switching power supplies.
Some known switching power converters accomplish higher efficiencies by zero voltage switching (ZVS). ZVS power converters can minimize switching losses.
A need exists for an improved power converter controller for various power converters. It is desirable to provide such an improved power converter controller that enables more effective controlled operation of power converters and that reduces output ripple. It is desirable to provide an improved power converter controller for an interleaved zero voltage switching (ZVS) forward power converter.
A principal object of the present invention is to provide an improved power converter controller for power converters. Other important objects of the present invention are to provide such an improved power converter controller for an interleaved zero voltage switching (ZVS) forward power converter; to provide such an improved power converter controller substantially without negative effect and that overcome many of the disadvantages of prior art arrangements.
In brief, a power converter controller and a method for controlling a power converter are provided. The power converter includes first and second power transformers, each having first and second primary windings and a secondary winding; and first and second switches that alternately couple primary windings of the first and second power transformers to an input power source. The power converter controller receives a feedback signal from the power converter. A voltage controlled oscillator responsive to the feedback signal provides a variable frequency signal. A phase shift controller coupled to the voltage controlled oscillator provides a variable phase shifted signal responsive to the variable frequency signal.